The disciplinary hearing of five students at the University of Sussex who were involved in student protests has been postponed due to claims the trial was being conducted by a biased chair.

Deputy vice-chancellor of the university, Prof Michael Davies, was set to preside over the hearing, but stepped down after advice from the students' legal representatives.

It was decided that he could not be seen as impartial as he had been appointed by the university and had already criticised the student occupation on Radio Sussex.

The panel, which also included academic representative Prof Liz James and the student union president Kelly McBride, must now be reconsidered.

Geoffrey Robertson QC, the prominent human rights barrister who represented the students, says: "[Disciplining the students] would set a very bad precedent for universities up and down the country, so that's what is at stake."

The students were part of the Occupy Sussex movement, which is campaigning against the privatisation of universities.

Last month, over 40 professors at the University of Sussex signed a letter in support of the students, highlighting doubts about the fairness of the trial.

In the letter, professors pointed to two key concerns they had with the hearing. The first was that, as the students were protesting against the policies of the vice-chancellor Michael Farthing, it was inappropriate to ask the deputy vice-chancellor to chair the hearing.

Professors also said that a message was posted on the university website on 9 December which "casts doubt on whether [the procedure] can be a fair process".

The message said: "These students were involved in organising or leading the repeated serious disruption of campus through occupations, which have been characterised by intimidating behaviour, theft, damage and violence."

The professors said these comments "prejudice the outcome of the disciplinary procedures".

Over 100 students, tweeting under the hashtag #sackfarthing, gathered outside the hearing to protest against the disciplinary action, which was heavily criticised last year when the university suspended the students from university grounds.

Michael Segalov, one of the students facing disciplinary action, says: "I don't think they were expecting this today, nor were they expecting the level of preparation and passion from the students and university staff involved.

"They expected students to come unprepared, scared and fearful. They thought we'd sit down, take a slap on the wrist and go away. Instead they were faced with one of the world's most prominent barristers.

"I suspect that the process by which we were invited to disciplinary action and suspended will have to be readdressed, as these decisions were made by people who clearly aren't impartial. Today has been an important day and a victory."

Occupy Sussex says: "The university will be forced to consider whether their kangaroo court will reconvene in a new form, faced with accusations of breaching human rights legislation, and neglecting to adhere to their duties under the Education Act, alongside national pressure from MPs, students and staff."

A spokesperson from the University of Sussex says: "Davies was asked to consider standing aside as chair and he agreed to step down to avoid any appearance of bias.

"We believe that he has acted properly and professionally throughout this process. The panel will be reconvened with a new chair in due course. The case in relation to the students still needs to be heard."

The result comes in the run-up to a meeting of students in Birmingham on 29 January to discuss the next steps for student activism, which saw a resurgence last year.